The Cessna 421 is an offshoot of the 401/411 family og planes. The 411 was an offshoot of the 310 series and was larger and featured more powerful engines than the 310. It provided room for a 2 man crew and 4-6 passengers/ The 411 first took flight in 1962 and 401 in 1965. The 401 and 402 were economical versions of the 411. The 401 featured a similar layout to 411 but the 402 was designed to be fast and easy to change between commuter and passenger use.

The 421 is innovative for the fact that it`s a pressurized twin engine plane designed for the business market. The pressurized fuselage uses an AiResearch pressuring system. The 421 was first flown in 1965 and received certification from the FAA in 1967. It began to be delivered to customers that same year.

The 421B was released in 1970 and featured a longer nose which could accommodate increased baggage and avionics components. It also had a wider wing span and stronger undercarriage and could carry a higher weight limit.